Submarine signaling system



April 14, 1925. 1,533,645

- J. J. GILBERT SUBMARINE SIGNALING SYSTEM Filed May 31, 1922071/6/7/0/1' x/0/7/7 u. (377k eff [by m/y Patented Apr. 14, 1925.

v, UNITED STATES PATENT OFFICE.

JOHN J. GILBERT, or PORT WASHINGTON, NEW YORK, ASSIGNOR TO WESTERN nLEc-Tnrc COMPANY, 'INconPoRA'rnn, or NEW YORK, Y.', AcoR-roRATIo on NEWYORK.

Application filed May 31,

To all whom it may concern:

Be it known that 1, JOHN J. Gincnn'r, a

citizen of-the United States of Americzn residing at Port \Vashington,in the county of Nassau and State of New York, have in-. vented certainnew and useful Improvements in SubmarineSignaling Systems, of which thefollowing is a full, clear, concise, and exact description.

This invention relates to artificial electric lines and to transmissionsystems, and more particularly submarine cable systems, iliWlliCh suchlines are employed.

An object of the invention is to provide an artificial line containinginductance and capacity for simulatingthe impedance of a submarine cableor other transmission con-- ductor, and designed so that oscillatorycurrents impulsively produced therein Will be confinedto a frequencyrange Which will reduce to a minimum their disturbing effect upon otherapparatus. i

In the following description of the inventionreference is made to theaccompanying drawing, in Which Fig. 1 is adiagrammatic showing ofterminal apparatus of a submarine signaling system according to thisinvention. Figs. 2, 3 and 4 represent cur rents set up in thisapparatus.

Referring to Fig. 1, a submarine cable A terminates in the usual duplexbridge arrangement in Which the cable forms one ratio arm, theartificial line AL the second arm and the condensers K, K the remainingarms. The transmitter T is connected be tween condensers K, K and groundand the receiving circuits RC and the receivingshaping network N are incircuit across the bridge in conjugate relation to the transmitter.

It is necessary to employ lun'iped or concentrated impedance elements inthe artificial line to simulate the distributed impedance of the cable.Since the cable is inductively loaded, the artificial line containslumped inductance as Well as lumped capacity and resistance, which aloneare ordi narily employed in the artificial lines of unloaded cablesystems. Each section. of this artificial line is seen to comprise thenecessary element-s of an oscillatory circuit. Then the localtransmitting key is operated, a relatively large current is impressedupon sUBMARI E SIGNALING sYs'rmvi.

current is shown in Fig." 4. '1

1922. Serial No. 564,915.

the cable and the artificialgline. 'lfheenergy thus impressed upon theartificial line i's first 65 stored in the reactive element-s, afterwhich a redistribution takes place in the natural periods of theoscillatory circuits. Thus iin pulsively produced oscillatory currentsare set up throughout the artificial line, and since no corresponding 1currents are 'pro ducedin the cable there is no balance with respect tothese currents, which flow through the shaping-receiving network intothe receiving instrument Where they mask the ,received signal, unlesssome means are pro, vided to preventthis action. Anobject of thisinvention is to overcome this disturb.-

ance. q V

Fig. 2 represents the instantaneous current impressed upon the 'cableand the ar tificial line by closure of. the transmitting key. Fig. 3representsthe' resulting current set up in a filtersection, Whichcurrent consists of the vertical front- 1 and the osoil latory portion2. The resultant disturbing he amount of interference with the receivedsignal, due to unbalance thus produced, depends upon the amplitudeandtheperiod of the several .80 pulses. The receiving apparatus is usuallydesigned to be highly sensitive to pulses having the same period asthose involvedin the received signal and to discriminate against pulseshavingshorter periods. If, as i for example, the signaling speed corre--sponds to 60 cycles per. second, the range [of frequencies involved insignaling is from 60 cycles'to two or threetimes' this frequency; a P

The periods-and amplitudes of the disturbing oscillatory currents can becalculated by mathematical formulae from which it appears that bothquantities decrease as the equivalent; length of a section of the pacityof .4 microfarads per nautical mile and an inductance of 60 millihenrysper nautical mile the period of the oscillations was found to be T:3.02TL where C and L are the values of the ca pacity and inductance in asection of the artificial line. If X is the equivalent length of thesection in nautical miles, then C:4 1O X, L:.O6X and .T:4.58 10X.According to this invention the value of X is chosen so that T is lessthan a prescribed value, which depends upon the degree of' greaterequivalent lengths; As shown in Fig. 1 each portion of the artificialline comprises two sections, but the use of a single section or a largernumber of sections is within the invention. The sections of portion Sare shown as comprising resistance R, inductance L and capacity C, thecorre' sponding elements of portion S having ref erence characters R Tand c respectively. The disturbing oscillation is the resultant of theeffects due to the various component artificial lines. The impulsingcurrent from transmitter T is large when impressed upon the firstportion S of the artificial line,'but is greatly attenuated by the timeit reaches portion S so that the amplitude of the dis- 1 turbingoscillations is relatively small. In

addition, the latter disturbances, in order to arrive at the receivermust traverse considerable lengths of the artificial line, and since theattenuation due to the line is very great'for the frequencies involvedin these disturbances, they will arrive at the receiver greatly reducedin amplitude. It is for these reasons that the equivalent length of eachsection of the portion S of the arti ficial line may be of suchmagnitude that the impulsively produced disturbing currents are withinthe range of-frequencies involved in the reception of the signal. Theyare so highly attenuated that thedisturbing effect is negligible. Theirfrequency of course may fall within a portion of the range to which thereceiving apparatus is not especially sensitive. If'desired, theartificial line could be extended to includeanother portion or portionshaving sections of equivalent lengths such that the frequency of thedisturbing currents would lie in a portion of the received frequencyrange to which the receiving instrument is more sensitive.

The invention has been described with special reference to a submarinesignaling system but it is obvious it is not so limited in itsapplication. The appended claims cover the invention both broadly andspecifically.

What is claimed is:

1. The combination at a signaling station of a souitce of signalingcurrent with a signal receiving means more readily responsive to certainfrequencies than to others, and an electrical network upon which currentfrom said source is impressed, said network comprising a plurality ofsections each having lumped inductance and capacity of such value thatoscillatory currents impulsively produced in said sections by saidsource of signaling current do not have frequencies to which saidsignaling means is readily responsive whereby the disturbing efi'ect ofsaid impulsively produced currents upon said signalreceiving means issmall.

2. The combination with a source of signaling current, of a signalreceiving device, and an electrical network upon which current from saidsource is impressed, said network comprising a plurality of sectionseach having lumped inductance and lumped capacity, the values of saidinductance and capacity for one or more sections electrically nearestsaid signal responsive device being I such that the frequency of theoscillatory current impulsivelyproduced therein by said sourceofsignaling current is such that the oscillatory current has a smalldisturbing effect only upon said signal responsive devlce, the capacityand inductance of another section or sections more remote from saidsignal responsive device having such values that the oscillatorycurrents impulsively produced therein are of a frequency which wouldcause a considerablev disturbing effect upon said'signal responsivedevice except for the remote association therewith.

3. The combination with a source ofsignaling current at a signalingstation, of a signal responsive device at said station, a second sourceof signaling current for transmitting signals through a transmittingmedium to said signal responsive device, and an electrical network atsaid station and upon which current from said first signaling source isimpressed, said network comprising a plurality of sections, eachcontaining lumped capacity and lumped inductance, the capacity andinductance of at least one of said sections electrically nearest saidsignal responsive device being so proportioned that the frequency of theoscillatory currents impulsively produced therein by said first sourceof signaling current is outside the range of frequencies received bysaid signal responsive device from said second source of signalingcurrent.

4. The combination with an inductively loaded submarine cable, ofconjugately related transmitting and receiving apparatus at eachterminal, and a balancing network ateach terminal to maintain saidconjugate relationship, said network comprising a plurality of sectionseach having lumped inductanceand lumped capacity, the capacity andinductance of the section or sections electrically nearest the receiverbeing proportioned so that the frequency of the oscillatory currents setup impulsively by the adjacent source of transmitted current is outsidethe range of frequencies involved in the reception of the signal,whereby the disturbing effect of unbalanced current is minimized.

5'. The combination with an inductively loaded submarine cable, ofconjugately rerelationship,

lated transmitting and receiving apparatus ateach terminal, and abalancing network at each terminal to maintain said conjugate saidnetwork comprising a plurality of sections each having lumped inductanceand lumped capacity, the capacity and inductance of the section orsections electrically nearest the receiver being proportioned so thatthe frequency of the oscillatory currents set up impulsively by theadjacent sources of transmitting current is outside the range offrequencies involved in the reception of signals, the inductance andcapacity of a section or sections of said network more electricallyremote from said receiver being so proportioned that the frequency orfrequencies of the impulsively produced oscillatory currents are withinsaid range.

In Witness whereof, I hereunto subscribe my name this 27th day of May,A. D. 1922.

JOHN J. GILBERT.

